Influence of biochar incorporation on TDR-based soil water content measurements
Influence of biochar incorporation on TDR-based soil water content measurements
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DOI：
10.1111/ejss.12083
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发表时间：
2014-01-01
影响因子：
4.2
通讯作者：
Shiono, T.
中科院分区：
文献类型：
--
作者：
Kameyama, K.;Miyamoto, T.;Shiono, T.
将生物炭（BC）掺入农业土壤中改变了土壤的物理性质，从而导致土壤的水力性质（例如保水性和渗透性）的变化，并改变农田中的土壤水分环境。为了阐明BC的掺入对土壤水分环境的影响，需要测量生物炭改良农田的土壤水分。时域反射仪（TDR）是一种广泛应用的连续测量农田土壤含水量（SWC）的技术。然而，TDR测量受到土壤电导率的影响。已知在较高热解温度下形成的生物炭是非常导电的。因此，我们研究了掺入BC对基于TDR的SWC测量的影响。我们研究了石灰性暗红色土壤和甘蔗渣在400、600和800 ℃下热解产生的BC。在一定的含水量下，BC（800 ℃）处理土壤的表观相对介电常数（ε（a））大于未处理土壤的表观相对介电常数（ε（a）），而BC（400 ℃）和BC（600 ℃）处理土壤的ε（a）值与未处理土壤相同。我们得出的结论是，当使用从非修正土壤获得的校准曲线时，基于TDR的测量往往会高估包含在较高热解温度下形成的BC的SWC，因为导电和介电损耗。因此，当对含有在较高热解温度下形成的BC的土壤进行基于TDR的含水量测量时，使用土壤的复相对介电常数的真实的分量（ε r）而不是ε r（a）是有效的。
The incorporation of biochar (BC) into agricultural soil changes the soil's physical properties, which leads to changes in the soil's hydraulic properties, such as water retention and permeability, and alters the soil moisture environment in agricultural fields. To elucidate the effects of the incorporation of BC on the soil moisture environment, measurements of the soil water in biochar-amended agricultural fields are needed. Time domain reflectometry (TDR) is a widely used and established technique for the continuous measurement of the soil water content (SWC) in agricultural fields. However, TDR measurements are affected by the conductivity of soils. Biochar formed at higher pyrolysis temperatures is known to be very conductive. Therefore, we investigated the influence of the incorporation of BC on TDR-based SWC measurements. We examined calcaric dark red soil and the BC produced by pyrolysis of sugarcane bagasse at 400, 600 and 800 degrees C. The apparent relative permittivity (epsilon(a)) of the BC (800 degrees C)-amended soil was greater than that of the non-amended soil at a given water content, whereas the epsilon(a) values of the soils amended with the BC (400 degrees C) and BC (600 degrees C) were the same as that of the non-amended soil at a given water content. We concluded that when a calibration curve obtained from a non-amended soil is used, TDR-based measurements tend to over-estimate the SWC containing the BC formed at higher pyrolysis temperatures because of conductive and dielectric losses. Therefore, the use of the real component (epsilon r) of the soil's complex relative permittivity instead of epsilon(a) is effective when making TDR-based water content measurements of soils that contain BC formed at higher pyrolysis temperatures.